1. Field of the Invention
The present invention relates to a semiconductor bonding structure and process and a semiconductor chip, and more particularly to a semiconductor bonding structure and process that can be completed in a low-temperature environment without use of solder.
2. Description of the Related Art
In a semiconductor flip-chip bonding process, a nickel layer is plated on a metal pillar of an upper chip to serve as a barrier layer, and then a solder is formed on the nickel layer. Next, the upper chip is placed on a lower chip or a substrate, so that the solder on the metal pillar contacts a surface finish layer on a bonding pad of the lower chip or the substrate. Then, a reflow process is performed, so that the solder is molten and bonded to the bonding pad, to form a flip-chip bonding structure.
In this process, a solder is used to attain bonding. Since the outer diameter of the solder cannot be effectively decreased, a pitch between metal pillars cannot be effectively reduced. In addition, in order to make the solder reach a molten state, the solder is heated to above 300° C., and in such a high-temperature environment, the upper chip and the lower chip or the substrate are prone to warping, and the metal pillar is easily oxidized. To avoid oxidation of the metal pillar, another known technique is to perform the high-temperature bonding step in a vacuum environment, which will increase the manufacturing cost, and still cannot solve the problem of warpage.
Therefore, it is desirable to provide a semiconductor bonding structure and process and a semiconductor chip, to solve the above problems.